Abstract: A flame detector includes an ultraviolet (UV) sensor to detect UV radiation emitted by a flame; a testing apparatus to periodically test function of the flame detector. The testing apparatus includes a UV light emitting diode (UVLED) emitter to emit a test signal and a mirror to reflect the test signal emitted from the UVLED emitter to the UV sensor. A method of testing an ultraviolet (UV) flame detector includes transmitting a test signal from a UV light emitting diode (UVLED) emitter. The test signal is reflected toward a UV sensor of the flame detector, and the test signal received at the UV sensor is evaluated.

Abstract: An apparatus for sensing a constituent in an environment including a sensor circuit and a suppression circuit. The sensor circuit has a sensor element and an operating state control element. The sensor element senses the constituent by presenting an electrical parameter which varies as a function of a degree of the constituent. The control element maintains the sensor at a preferred operating state. A detected electrical parameter of said sensor element is subject to error resulting from a leakage of electrical current between the control element and the sensor element. The suppression circuit reduces or stops the leakage to reduce the error.

Abstract: An apparatus and method for performing first and second imaging processes contemporaneously, in particular where one of the processes is detecting fires based on images of the flames. The apparatus includes an image sensor for producing a video image, a frame grabber for capturing first frames and second frames, a processor for processing the data within the frames, and an output device. The apparatus may also include an adjustment mechanism for adjusting the image settings of the image sensor between settings suitable for flame imaging and non-flame imaging, and a control mechanism for controlling the image settings of the image sensor. In the method at least two first frames are obtained, and a plurality of second frames are obtained. The first and second frames are used for first and second processes. The first and second processes are contemporaneous, so that they are carried out within the same time period without interfering with one another.

Abstract: To detect flames burning carbon-free hydrogen-bearing fuels, first, second, and third sensors sense first, second and third regions of an infrared water emission band, and generate first, second, and third signals. A processor generates an alarm when the sensors indicate flame. The first region low cut-off wavelength may be lower than the second region low cut-off wavelength. The third region high cut-off wavelength may be higher than the second region high cut-off wavelength. The combined regions may include nearly the entire water emission band. The processor may discriminate distances to flames using the sensor signals. A fourth sensor may sense moisture concentration, and the processor may discriminate distances based thereon. The regions may be defined such that for a fire, all three regions receive substantial energy, with second region to first region energy ratio less than 1:1 and a second region to third region energy ratio less than 1:1.

Abstract: An apparatus and method for open-path gas detection. The apparatus includes a radiation source and first and second radiation detectors sensitive to radiation in first and second spectral bands. The long cut-off wavelength of the second spectral band is longer than the long cut-off wavelength of the first spectral band, and the short cut-off wavelength of the second spectral band is shorter than the short cut-off wavelength of the short spectral band, such that the second spectral band is wider than and completely overlaps the first spectral band. Radiation from the radiation source passes through the area to be checked for gas, and is partially absorbed if gas is present. The path between the radiation source and the first and second radiation detectors need not be enclosed, and may exceed 100 meters in length. A processor compares intensity signals from the radiation detectors with a threshold value, and generates an output signal indicating a presence of gas based on the comparison.

Abstract: An apparatus and method for performing first and second imaging processes contemporaneously, in particular where one of the processes is detecting fires based on images of the flames. The apparatus includes an image sensor for producing a video image, a frame grabber for capturing first frames and second frames, a processor for processing the data within the frames, and an output device. The apparatus may also include an adjustment mechanism for adjusting the image settings of the image sensor between settings suitable for flame imaging and non-flame imaging, and a control mechanism for controlling the image settings of the image sensor. In the method at least two first frames are obtained, and a plurality of second frames are obtained. The first and second frames are used for first and second processes. The first and second processes are contemporaneous, so that they are carried out within the same time period without interfering with one another.

Abstract: An optical fire detector employs two or more sensors operating a different spectral bands. The spectral bands are selected to have approximately coincident cut-off wavelengths in order to make the detector's ability to positively identify a fire more uniform over its field of view. The use of three overlapping spectral bands provides the detector with enhanced detection capabilities for large, hot fires that behave like black body radiators.

Abstract: A method for extracting a number of temporal frequencies occurring in a fire and false fire condition concurrently from two or more radiation detectors for receiving signals, a correlation detector for each frequency and sensor, and a storage buffer for the temporal frequencies extracted and sensors employed, so as to distinguish a small fire signal in the presence of a much larger false fire signal whether random in nature or not. The ratio of each extracted frequency following proper qualification is compared to the ratio band for fire and an output signal is generated when the ratio at one or more temporal frequencies indicates a fire.

Abstract: A swivel mounting bracket for attachment to an electrical junction box and to a detector device, the swivel mounting bracket having two identical fittings. Each fitting has an internal passageway which progresses around a 90.degree. bend, and each fitting has a mounting plate at one end and a mounting base at the other end, positioned orthogonal to each other. Each mounting plate has an arcuate groove with an internal shoulder for facilitating attachment to a mounting base. The mounting base of one fitting is attachable to the mounting plate of the other fitting, and the respective remaining fitting ends are attached to the junction box at a detector.

Abstract: A radiation detector having wide-range sensitivity is provided. In accordance with one embodiment of the invention, a radiation detector for detecting a radiation condition is provided. The radiation detector includes a plurality of sensors each of which detect radiation in a spectral band and output an analog signal in response to the amount of radiation in the spectral band, a converter system associated with each of the sensors for converting each analog signal to a digital signal, and a processor coupled to the converter system for using the digital signals to output a detection signal. The converter system has a sensitivity range which includes a minimum magnitude and a maximum magnitude of the analog signals. The processor can detect the radiation condition in an environment which concurrently induces the minimum magnitude in the analog signal of one of the sensors, and the maximum magnitude in the analog signal of a different one of the sensors.

Abstract: A ruggedized gas detector having two or more perforated concentric cylinders and having a concentric screen inside the innermost cylinder. A pair of perforated tubes are positioned inside the perforated screen, and an infrared light source is placed adjacent one end of one of the tubes and an infrared sensor is placed adjacent the other tube. A pair of inclined mirrors are positioned adjacent the respective other ends of the two tubes, and an optical light path is created from the IR source through a first tube, reflected by the mirrors to a return optical path through the second tube and ultimately to the IR sensor.

Abstract: A system for detecting and isolating faults in a two-wire communications loop which includes a number of node circuits dispersed along the loop. Each node circuit executes a fault detection algorithm and selectively switches its connections to adjacent node circuits to effectively isolate itself from the fault condition. When all node circuits have completed their respective fault detection algorithms the fault condition is disconnected from the two-wire communications loop.

Abstract: A system for detecting randomly occurring signals, particularly signals representative of a fire condition, having a radiation detector for receiving the signals, peak detector circuits for identifying the peak values of the received signals, peak duration signals for determining the time between adjacent peak signals, and a collection buffer for accumulating values representative of successive peak durations. The peak duration times are compared and evaluated to determine whether regularly occurring patterns of the received signals exist, or whether the received signals are randomly occurring, and an output signal is generated whenever the comparison indicates that the received signals are random in nature.

Abstract: An apparatus and method for sensing electro-magnetic radiation and analysing the resultant electrical signal waveform, in order to determine whether the radiation originates from a fire condition, monitors variations in the signal waveform over a predetermined period of time. The amplitudes of the successive transitions in the waveform and the elapsed time between the transitions are measured. Two two-dimensional matrices are produced. The first of these is made up of a plurality of co-ordinate points each corresponding to a respective pair of successively occurring signal transitions. The position of each such point in the matrix is dependent on the respective amplitudes of the two transitions making up each pair. The second matrix is also made up of a plurality of co-ordinate points each corresponding to a respective pair of the signal transitions.

Abstract: The linearity of a photoresistive device at varying levels of radiant signal is improved by masking the sensitive area of the photoresistive device so that only a portion of the sensitive area is illuminated. The masking prevents exposure of the entire surface area of the cell, which increases the dynamic range, allowing a more linear, small signal sensitivity over wide variations in brightness.

Abstract: A flame detector has a sensor for producing a digital waveform representing a flickering flame. Its turning points are detected and the magnitudes between successive such points are measured. The value of each such magnitude is plotted on a graph whose horizontal axis represents the current value and whose vertical axis represents the immediately preceding value. Points are produced lying in regions away from the diagonal and from the axes. If the detected waveform originates from a regularly varying interfering source, the corresponding points will lie on or near the diagonal. If the interfering source is a waveform undergoing step changes, the corresponding points will lie adjacent to the axes. In this way, discrimination between flames and interfering sources of radiation can be made.

Abstract: Apparatus for detecting radiation with a light-sensitive radiation receiving tube enclosed in a housing behind a transparent window, the invention including an auxiliary internal light source for testing the optical transmissive properties of the window and including a shielding member between the auxiliary light source and the radiation-receiving tube and a reflective mirror for directing light from the auxiliary light source toward the window for reflection off an external interface surface thereof toward the radiation-receiving tube.

Abstract: A random signal isolation circuit connectable to a source of signal generation wherein signals of interest tend to occur at relatively closely spaced intervals, and noise signals tend to occur at random time intervals, including a first multivibrator trigger circuit which triggers on the falling edge of a received signal, and a second multivibrator trigger circuit which triggers on a rising edge of a received signal, the first multivibrator circuit being connected when triggered to enable the second multivibrator trigger to receive subsequent received signals. The first multivibrator trigger circuit is activated over a predetermined time delay, and at the end of the time delay disables the second multivibrator trigger circuit.

Abstract: Apparatus for detecting flame or smoke, having a radiation detection tube enclosed in a housing, facing the exterior through a transparent window at one end of the housing, and having a radiation source proximate the other end of the housing and external the tube housing, with an optical path exterior of the housing from the radiation source to a reflector ring positioned in front of the transparent window and in a direction to deflect radiation from the radiation source through the transparent window to the radiation detection tube. The invention also includes a second internal radiation source optically coupled to the radiation detection tube for providing a reference radiation, which not only provides a comparison base for radiation received by the radiation detection tube from external radiation sources, but also provides a monitor function to evaluate the quality of the optical path through the window and to check the operation of the radiation detection tube and related circuits.

Abstract: Circuitry directed to the rapid de-ionization of ultraviolet detectors by increasing the mobility of the ionized gases within the tubes which will enable the tubes to more effectively operate at low temperatures. The circuitry includes connecting circuitry for shorting the elements of the tube such that they will be at the same potential immediately after firing and also includes circuitry for the shunting of the tube immediately after firing to limit the number of ions generated in the discharge process. The shorting of the elements increases the surface area of negative electrodes for the recapture of the ions and the distance through which the ions must travel is reduced by a factor of one-half.